This project is a continuation of a previous program designed to achieve the following ends: (1)\to isolate and characterize the abnormal immunoglobulins appearing in the blood and urine of patients with multiple myeloma, macroglobulinemia, and related lymphomas; (2)\to study the chemical, physical, and immunological properties of immunoglobulins IgM, IgA, IgG, and IgD and also their relationships to each other and to Bence Jones proteins and normal immunoglobulins; (3)\to do complete amino acid sequence analysis of Bence Jones proteins and the light chains of the immunoglobulins; and (4)\to undertake complete amino acid sequence analysis of the heavy chains of IgA, IgD, and IgG myeloma globulins and of pathological IgM human macroglobulins. The overall purpose is to ascertain the structural relationships among these proteins in relation to the problems of immunoglobulin biosynthesis, evolutionary development, genetic control, and antibody specificity and to develop information, reagents, and procedures of value for study of lymphomas and autoimmune diseases. Recent accomplishments include: (1)\determination of the complete primary structure of human myeloma IgD proteins: (2)\study of the proteolytic cleavage of immunoglobulins and of the structural and biological properties of the fragments; (3)\isolation and structural study of the glycopeptides and carbohydrate of myeloma proteins. Current effort is directed toward study of the serum and urinary proteins characteristic of heavy-chain disease, a rare lymphoma. (AB)